Ministers have repeatedly argued that Britain has had no need of either HMS Ark Royal or the Harriers in the Libyan mission because planes can fly from bases in Italy, such as Gioia del Colle.

But Sir Mark said the carrier and its planes would have been useful in Libya. "If we had Ark Royal and the Harriers, I feel relatively reassured that we would have deployed that capability off Libya," he said.

Harriers would have been used for "ground support" operations, attacking Col Gaddafi's land forces, he said.

Sir Mark appeared to contradict ministers' assurances on the Italian bases. He said operating Harriers from an aircraft carrier would have allowed British forces to respond more quickly to events on the ground in Libya.

"The pros would have been a much more reactive force," he said. "Rather than deploying from Gioia del Colle, we would deploy within 20 minutes as opposed to an hour and a half, so obviously there are some advantages. It's cheaper to fly an aircraft from an aircraft carrier than from the shore." Scrapping Ark Royal and its Harriers was perhaps the most controversial decision made in last year's Strategic Defence and Security Review. The Coalition has said it could not afford to maintain the ship or the planes. Military analysts and retired defence chiefs have said the cuts have limited Britain's military capabilities.

Despite his remarks, Sir Mark said there could be no going back on the cuts. "We have got to look forward."

British forces have been in action in Libya since March, yet Col Gaddafi remains in power. On June 1, Nato extended the military mission by another 90 days.

Sir Mark said British forces would be "comfortable" with another three months of operations.

"Beyond that, we might have to request the Government to make some challenging decisions about priorities," he said. "There are different ways of doing this. It's not simply about giving up standing commitments, we will have to rebalance."

Robert Gates, the US defence secretary, said last week that Britain and France were struggling to maintain the Libyan operation without significant American support and supplies.

Sir Mark confirmed that the Navy had been forced to ask the US to resupply Tomahawk cruise missiles used by submarines targeting Libya.

"We are not running out, but we certainly have to take action to replace those weapons to bring stockpiles back up to where they were," he said.

As well as Ark Royal and the Harriers, the Navy is losing 5,000 posts under the defence review.

Rear-Adml David Steel, the head of Navy personnel, said the defence cuts would be a major challenge for the Senior Service.

"Our ships are hugely capable but we just don't have enough of them," he told a veterans' conference in Plymouth at the weekend.

"Having to make so many people redundant would be almost comical if it were not so serious."

Dr Liam Fox, the Defence Secretary, defended the defence review last night. He said: "We continue to have the resources necessary to carry out the operations we are undertaking."

An MoD source said: "Unfortunately Harriers wouldn't have been able to carry the precision weapons needed for these operations."